1. Field of the Invention
The present invention relates to a novel organosilicon compound, a thermosetting resin composition containing the compound useful for such purposes as a coating material, an optical material and an electric insulating material, and a cured material which is obtained by thermally heat-curing the composition.
2. Related Art
In recent years, an illumination device, such as a light emitting diode (LED), which is subjected to practical use as a display board, a light source for an image scanner, a traffic signal, a large-sized display unit, a backlight for a mobile phone, and the like, is generally produced by sealing with a resin system, which contains an aromatic epoxy resin having an alicyclic acid anhydride added thereto as a curing agent. However, it has been known that the resin system is liable to suffer discoloration of the acid anhydride due to an acid, and requires a prolonged period of time for curing. Furthermore, the resin system has a problem of yellowing of the sealing resin when the sealing resin is exposed outdoors or exposed to a light source emitting an ultraviolet ray.
For solving the problems, it has been proposed that an LED or the like is sealed with an alicyclic epoxy resin or an acrylic resin cured with a cationic polymerization initiator (see, for example, JP-A-61-112334 and JP-A-2-289611). However, the cured resin having been cationically polymerized has such severe defects that the cured resin is extremely brittle and thus is liable to suffer breakage due to cracking through a cold cycle, and suffers significant discoloration of the sealing resin after curing as compared to the conventional curable resin system containing an aromatic epoxy resin and an acid anhydride. Accordingly, the curable resin system employing cationic polymerization is not suitable for a purpose that requires colorless transparency, particular not suitable for a purpose of sealing an LED, which requires heat resistance and transparency.
JP-A-2003-277473 discloses a resin composition for an LED sealing material that is prevented from suffering cracks through a cold cycle and is excellent in light fastness. The resin composition contains a hydrogenated epoxy resin or an alicyclic epoxy resin as a matrix component, but the resin composition suffers significant discoloration after curing and thus still has room for improvement in discoloration.
JP-A-2004-27186 discloses a potting resin composition containing an alicyclic epoxy resin or an oxetane resin as a viscosity decreasing agent for filling a gap between a circuit board and an electronic part disposed thereon. However, the resin composition contains a large amount of an inorganic filler and thus cannot be applied to a purpose that requires transparency. WO 01/072857 discloses an alkali aqueous solution-soluble resin composition containing a modified oxetane resin as an active energy ray-curable resin, but what is disclosed in this reference is to intend to provide an alkali-soluble resin, and a modified oxetane resin and a polyfunctional oxetane resin unavoidably suffer discoloration through thermal history due to an unsaturated bond contained therein.
JP-A-2006-070049, WO 2004/081084, JP-A-2004-331647, WO 2003/24870 and WO 2004/24741 each disclose a cage silicon compound and a polymer thereof, but fail to disclose the organosilicon compound and the thermosetting resin composition containing the same according to the invention.